Various f in structures have been proposed for a fin tube heat exchanger having multiple parallel fins and multiple heat transfer tubes arranged to pass through the multiple fins. One proposed structure is slit fins with long slits (see, for example, Patent Document 1). Another proposed structure is corrugated fins having concaves and convexes arranged perpendicular to an air flow direction (see, for example, Patent Document 2). These proposed fin structures aim to promote the heat transfer performance in the fin tube heat exchanger.
Patent Document 1: Japanese Patent Laid-Open No. 2003-161588
Patent Document 2: Japanese Patent Laid-Open No. 2000-193389